Castor seed-derived luminescent carbon nanoparticles for metal ion detection and temperature sensing applications

Abstract

In the current study, castor seeds are used as a first-time natural precursor in the hydrothermal process of making carbon nanoparticles. The produced nanoparticles have a non-uniform size distribution with an average diameter of 13 nm and a roughly spherical shape. They comprise a variety of functional groups containing carbon, nitrogen, and oxygen. Their spectra have peaks at 524 nm and 441 nm for their emission and excitation, respectively. They exhibit temperature-sensitive Photoluminescence (PL) behaviour, high quantum yield value (24%), and excitation-dependent emission. In high salt environments, UV radiation, storage time, and fluorescent light they provide exceptional photostability. They have been used in applications for metal ion and thermal sensing. With a limit of detection (LOD) value of 18 μM, they are found to be both sensitive and selective to Fe3+ ions. Additionally, a nanothermosensor with good recovery and a broad temperature range (5 °C–85 °C) has also been demonstrated with a thermal sensitivity of 0.54% °C−1 based on their temperature-sensitive behaviour.